The present invention relates to wound healing devices. More particularly, the invention relates to a therapeutic foot wrap for application of positive pressure to the first and fifth metatarsal head and heel regions of a patient suffering diabetic ulceration and/or like wounds.
An ulcer is commonly defined as a lesion on the surface of the skin, or on a mucous surface, manifested through a superficial loss of tissue. Ulcers are usually accompanied by inflammation and often become chronic with the formation of fibrous scar tissue in the floor region. Chronic ulcers are difficult to heal; they almost always require medical intervention and, in many cases, lead to amputation of the limb upon which they occur.
In general, ulcers may be attributed to any of a variety of factors reducing superficial blood flow in the affected region. Leg (including the foot) ulcers, in particular, are attributable to congenital disorders, external injury, infections, metabolic disorders, inflammatory diseases, ischaemia, neoplastic disorders and, most commonly, arterial disease, neuropathic disorders and venous insufficiency. Neuropathic and ischaemic ulcers commonly manifest in association with diabetes and, for this reason, are often referred to as diabetic ulcers. Although certainly not exhaustive, the table entitled Common Etiology of Leg Ulcers, highlights the frequency at which patients are placed at risk for the formation of this potentially devastating disease.
Perhaps as striking as the incidence of this disease, is the magnitude of the resources dedicated to the combat of its occurrence. It is estimated that leg ulcers cost the U.S. healthcare industry in excess of $1 billion annually in addition to being responsible for over 2 million annual missed workdays. Unfortunately, the price exacted by ulcers is not merely financial. Leg ulcers are painful and odorous open wounds, noted for their recurrence. Most tragic, diabetic ulcers alone are responsible for over 50,000 amputations per year. As alarming as are these consequences, however, the basic treatment regimen has remained largely unchanged for the last 200 years. In 1797, Thomas Baynton of Bristol, England introduced the use of strips of support bandages, applied from the base of the toes to just below the knee, and wetting of the ulcer from the outside. Standard of care treatment for ulcers affecting the foot has developed little beyond prevention oriented approaches. When management of the underlying disease condition fails to prevent ulcer formation, debridement and occlusive bandaging is about the only remaining option. As discussed in more detail herein, versions of these therapies remain the mainstay treatment to this day and, clearly, any improvement is of critical importance.
As noted above, the most common causes of leg ulcers are venous insufficiency, arterial disease, neuropathy, or a combination of these problems. Venous ulcers, in particular, are associated with abnormal function of the calf pump, the natural mechanism for return to the heart of venous blood from the lower leg. This condition, generally referred to as venous insufficiency or venous hypertension, may occur due to any of a variety of reasons, including damage to the valves, congenital abnormalities, arteriovenous fistulas, neuromuscular dysfunction, or a combination of these factors. Although venous ulcers tend to be in the gaiter area, usually situated over the medial and lateral malleoli, in severe cases the entire lower leg can be affected, resembling an inverted champagne bottle.
Diabetic and arterial ulcers, in particular, are associated with degenerative disease resulting in progressively narrowed vessel lumen which, in turn, causes obstructed blood flow. These types of ulcers are frequently found at sites of localized pressure or trauma. The diabetic patient (neuropathic ulcers), who may also suffer arterial disease, will often have impaired sensation in the foot area and will therefore likely be unaware of repeated trauma. This exacerbates ulceration in the traumatized or pressure-bearing areas, commonly the first and fifth metatarsal heads and over the heel.
Clinical modalities for prevention of venous ulcers generally focus on the return of venous blood from the lower extremities to the heart. Mechanical prophylaxes are widespread in the art of prevention and are often referred to as foot pumps or wraps, leg pumps or wraps and sequential compression devices, all of which function to prevent deep vein thrombosis (xe2x80x9cDVTxe2x80x9d), a common precursor to venous stasis ulcers. An exemplary foot pump is commercially available from Kinetic Concepts, Inc. of San Antonio, Tex. under the trademark xe2x80x9cPLEXIPULSE.xe2x80x9d An exemplary sequential compression device is described in U.S. Pat. No. 5,031,604 issued Jul. 16, 1991 to Dye (xe2x80x9cDyexe2x80x9d).
As generally described in Dye, mechanical prophylaxes for DVT prevention are directed toward the improvement of venous return. To this end, devices like that of Dye are adapted to take advantage of the naturally occurring valvular structure of the veins to squeeze the blood from a patient""s limb. For instance, the trademark xe2x80x9cPLEXIPULSExe2x80x9d device is adapted to intermittently compress the patient""s plantar venous plexus, promoting the return of blood from the patient""s foot upward and through the calf region. Likewise, and as generally described at column 2, lines 33 et seq. of Dye, leg compression devices are usually adapted to squeeze the patient""s leg first near the ankle and then sequentially upward toward the knee. This milking-type sequence may or may not be performed on a decreasing pressure gradient, but is always designed to move blood from the extremity toward the heart. It should be noted at this time that these types of devices are generally not appropriate for use in the intended function of the present invention as the described wraps tend to produce a shearing force in the region of the first and fifth metatarsal heads and over the heel.
Treatment of venous ulcers, on the other hand, is predominately centered about gradient compression, through bandaging, and leg elevation. Although it is not precisely known how or why they improve venous ulcer healing, compression therapies, specifically including compression bandaging techniques, are now the well-established mainstay for the treatment of venous stasis and other ulcers. In fact, it is generally undisputed that compression bandaging is the most efficacious method for wound healing, often resulting in overall improvement of the patient""s quality of life.
Among the predominant theories for explaining the effects of compression bandaging, edema reduction and control for the improvement of venous hemodynamic abnormality concomitant prolonged venous hypertension from valvular incompetency or dysfunction stands out. It is thought that the reduction and control of edema improves capillary microcirculation, in turn resulting in the elimination of venous ulcers. Another popular theory holds that reactive hyperemia is responsible for the success of compression bandaging. According to this theory, the arrest and subsequent restoration of blood flow to the affected region, known as Bier""s method, results in an ultimately increased presence of blood in the region. Regardless of the theory adopted, however, it is important to note that it is universally understood that a proper gradient must be established in order to derive the benefits of compression bandaging. This gradient is generally accepted as being from about 35 to 45 mm Hg at the ankle and reducing to about 15 to 20 mm Hg at just below the knee. Often stated in the literature as a prerequisite to good bandaging technique, the maintenance of graduated compression is critical to effective treatment of ulcers. Failure to initially obtain, and thereafter maintain, the desired sub-bandage pressures is fatal to the treatment regimen.
The criticality of establishing and maintaining the desired sub-bandage pressure directly results in significant disadvantages, associated with the application of compression bandaging in general, and serious hazards to the patient, associated with the misapplication of bandaging specifically. In particular, proper bandaging under the presently known methods requires a highly skilled caregiver in order to establish the desired sub-bandage pressures. Once established, however, the pressure gradient is difficult to monitor. In fact, the sub-bandage pressure is usually only monitored to the extent that the caregiver either observes or fails to observe a reduction in edema. This is particularly disturbing when one considers that it is to be expected that as properly applied bandaging performs its intended function edema will be reduced causing, in effect, the bandage to become loosened to a state of improper application where after edema will probably increase. More disturbing is the fact that over tightening of the bandage places the patient at direct risk for skin necrosis and gangrene, especially if the patient has arterially compromised limbs.
Unfortunately, there has been surprisingly little development in treatment protocols directed toward better achieving desired sub-bandage pressures. Even though the foregoing discussion highlights the necessity for frequent reapplication of the bandaging, the presently available treatment modalities are very difficult to apply. One common type of bandaging comprises four layers, including an orthopedic wool layer, a crepe bandage layer and two compression layers. The compression layer bandages are often provided with imprinted rectangles that become square upon achieving the correct tension. Although helpful, only two sets of markings are typically providedxe2x80x94one for normal size ankles and one for larger, and no provision is made for adaptation to changes in the level of edema. Another common treatment modality is the compression dressingxe2x80x94an elastic support stocking providing a compression of about 30 to 40 mm Hg. These stockings, however, are often impractical for elderly patients or patients with arthritis who may find them difficult to put on the leg and for the patient with large or exudative ulcers, which require frequent dressing changes, compression stockings are thought to be prohibitively impractical. While the foregoing discussion makes clear that the theory of compression bandaging, albeit limited in application, is sound for the treatment of wounds, it is unfortunately very difficult to extend to treatment of wounds on or about the feet. Compression bandages simply are not readily adapted for application to a foot.
As this discussion makes apparent, the need for treatment modalities beyond the presently known compression bandaging techniques is great. Unfortunately, the mechanical prophylaxes utilized in prevention therapies are not generally extendable to wound healing. Although, recent reports have indicated that achieving sustained sub-bandage pressures near 40 mm Hg may be more efficacious in providing timely wound healing than lower pressure levels and the present applicant has found that mechanical prophylaxes are generally better able to deliver higher pressures, caution is warranted. Because some 20 percent or more of patients with venous ulcers may also have some degree of co-existing lower extremity arterial disease, it is important to clarify the possible impact of higher levels of compression bandaging on lower extremity skin circulation. Studies show that mechanically produced compression levels may produce ischaemic not noted at similar compression levels obtained through bandaging. The reductions in leg pulsatile blood flow associated with mechanical prophylaxes often occur at compression levels below that necessary for good bandaging effects. This result, sometimes called cuffing, has resulted in most mechanical prevention prophylaxes being contraindicated for patients exhibiting DVT. Consequently, those of ordinary skill in the art have to date steadfastly avoided mechanical prophylaxes for the treatment of venous stasis and other ulcers or edema of the extremities.
The end result is that the patient once suffering from diabetic ulcers is left at the mercy of an extraordinarily high recurrence rate and is thought to be at severe risk for eventual amputation. This leads to emotional complication of the treatment process. Because preventing recurrence is as great a challenge as healing the ulcer, new and improved methods and apparatus for treatment of leg ulcers are desperately needed. In addition, because careful skin care and compression therapy must continue throughout the patient""s lifetime, it is imperative to the patient""s long-term health care to provide a low-cost, easily applied solution with which the patient may be assured of receiving effective therapy.
Additionally, many other problems, obstacles and challenges present in existing modalities for the treatment of leg ulcers will be evident to caregivers and others of experience and ordinary skill in the art. With the severe shortcomings of the prior art in mind, it is an overriding object of the present invention to improve generally over the prior art in providing a wound treatment apparatus that is adaptable to the changing physiology of a patient, is simple to use and is sure to produce the desired treatment.
In accordance with the foregoing objects, the present inventionxe2x80x94a foot wrap for the promotion of healing ulcers and like wounds of the footxe2x80x94generally comprises a multi-layered sheet structure for removable application to a patient""s foot, having interposed therein an integral bladder, and an inlet for fluid inflation of the bladder. The sheet structure is preferably adapted and the bladder is preferably shaped to produce a non-shearing compressive force in the area of the patient""s first and fifth metatarsal heads upon fluid inflation of the bladder.
Finally, many other features, objects and advantages of the present invention will be apparent to those of ordinary skill in the relevant arts, especially in light of the foregoing discussions and the following drawings, exemplary detailed description and appended claims.